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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #145903
Title: EFFECTS OF CALVING DATE AND WEANING AGE ON COW AND CALF PRODUCTION IN THE NORTHERN GREAT PLAINS

Author
item Grings, Elaine
item SHORT, ROBERT - RETIRED ARS
item Heitschmidt, Rodney

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2003
Publication Date: 6/1/2003
Citation: GRINGS, E.E., SHORT, R.E., HEITSCHMIDT, R.K. EFFECTS OF CALVING DATE AND WEANING AGE ON COW AND CALF PRODUCTION IN THE NORTHERN GREAT PLAINS. JOURNAL OF ANIMAL SCIENCE SUPPLEMENT ABSTRACT #662. 2003. v. 81(SUPPL. 1). p. 169.

Interpretive Summary: A 3-year study evaluated late winter (Feb), early spring (Apr), and late spring (Jun) calving systems (CS) on beef cow and calf performance. Crossbred cows were randomly assigned to 1 of 3 CS (avg n/CS/yr = 148) and 1 of 2 weaning times (Wean 1, 2) within each CS. Feb and Apr calves were weaned at 6- and 8-mo of age; Jun calves were weaned at 4- and 6-mo of age. Breeding by natural service occurred in a 32-d period that included estrus synchronization. Early weaned steers were housed in feedlots while half of the early weaned heifers grazed improved pastures and half were housed in feedlots. Early weaned calves were weighed on approximately the same day as late weaning. Weaning weight of calves adjusted to a constant date (October 19) was decreased (P < 0.01) as calving time became later (273, 229, and 181 kg for Feb, Apr, and Jun calves, respectively). Jun calves (203 kg) were lighter (P < 0.01) than Feb (224 kg) and Apr (221 kg) calves at 190 d of age. A CS x Wean interaction (P < 0.01) occurred for calf gains between Wean 1 and 2. Gains for early weaned calves averaged 0.71, 0.56, and 0.56 and for late weaned calves averaged 0.75, 0.47, and 0.56 kg/d for Feb, Apr, and Jun, respectively. Between weanings, suckled cows gained less (Feb: Wean 1, 23.0 kg vs Wean 2, 6.0 kg) or lost more than non-suckled cows in all herds (P < 0.01). Cow weight change between Oct (Wean 1) and Dec (Wean 2) did not differ for Apr and Jun (-1.7 kg) non-suckled cows, but loss was greater for suckled Jun (-35.0 kg) than Apr (-15.4 kg) cows (CS x Wean interaction, P < 0.01). Time of weaning did not affect (P > 0.10) subsequent year's cow or calf performance at weaning. Pregnancy rates (87.9%) were not affected (P > 0.10) by CS. Season of calving and weaning age have significant impacts on outputs from rangeland-based beef cattle operations.

Technical Abstract: A 3-year study evaluated late winter (Feb), early spring (Apr), and late spring (Jun) calving systems (CS) on beef cow and calf performance. Crossbred cows were randomly assigned to 1 of 3 CS (avg n/CS/yr = 148) and 1 of 2 weaning times (Wean 1, 2) within each CS. Feb and Apr calves were weaned at 6- and 8-mo of age; Jun calves were weaned at 4- and 6-mo of age. Breeding by natural service occurred in a 32-d period that included estrus synchronization. Early weaned steers were housed in feedlots while half of the early weaned heifers grazed improved pastures and half were housed in feedlots. Early weaned calves were weighed on approximately the same day as late weaning. Weaning weight of calves adjusted to a constant date (October 19) was decreased (P < 0.01) as calving time became later (273, 229, and 181 kg for Feb, Apr, and Jun calves, respectively). Jun calves (203 kg) were lighter (P < 0.01) than Feb (224 kg) and Apr (221 kg) calves at 190 d of age. A CS x Wean interaction (P < 0.01) occurred for calf gains between Wean 1 and 2. Gains for early weaned calves averaged 0.71, 0.56, and 0.56 and for late weaned calves averaged 0.75, 0.47, and 0.56 kg/d for Feb, Apr, and Jun, respectively. Between weanings, suckled cows gained less (Feb: Wean 1, 23.0 kg vs Wean 2, 6.0 kg) or lost more than non-suckled cows in all herds (P < 0.01). Cow weight change between Oct (Wean 1) and Dec (Wean 2) did not differ for Apr and Jun (-1.7 kg) non-suckled cows, but loss was greater for suckled Jun (-35.0 kg) than Apr (-15.4 kg) cows (CS x Wean interaction, P < 0.01). Time of weaning did not affect (P > 0.10) subsequent year's cow or calf performance at weaning. Pregnancy rates (87.9%) were not affected (P > 0.10) by CS. Season of calving and weaning age have significant impacts on outputs from rangeland-based beef cattle operations.